In recent years, OCT that forms images representing surface and/or internal morphology of objects using light beams from laser light sources etc. has attracted attention. Unlike X-ray CT, OCT is noninvasive to human bodies and is therefore expected to be utilized in medical and biological fields in particular. For example, in ophthalmology, apparatuses for forming images of fundus, cornea, etc. are in practical stages.
Patent Document 1 discloses an apparatus that uses so-called “Fourier Domain OCT” technique. Specifically, this apparatus irradiates low-coherence light beam to an object, superposes its reflected light and reference light to generate interference light, acquires spectral intensity distribution of the interference light, and executes Fourier transform on it to image morphology of the object in a depth direction (z-direction). Further, this apparatus is provided with a galvano mirror for scanning light beams (signal light) in one direction (x-direction) perpendicular to the z-direction, and forms an image of a desired measurement target region of the object. An image formed by this apparatus is a two-dimensional cross-sectional image along the depth direction (z-direction) and scanning direction (x-direction) of the light beam. Such a technique is specifically called Spectral Domain. Patent Document 2 also discloses an OCT apparatus of Spectral Domain type.
Patent Document 3 discloses an OCT apparatus that scans wavelengths of light irradiated to an object (wavelength sweeping), detects interference light obtained by superposing reflected lights of the respective wavelengths on reference light to acquire spectral intensity distribution, and executes Fourier transform on it to image morphology of the object. Such an OCT technique is called Swept Source etc. Swept Source type is a kind of Fourier Domain type. Patent Document 4 discloses a configuration in which OCT is applied to ophthalmology.
OCT apparatuses have advantages in that high-definition images may be obtained, cross-sectional and three-dimensional images may be obtained, etc.